Soap manufacture



Jan. 10, 1956 P. BRADFORD SOAP MANUFACTURE Filed May 21, 1951 2 g ,4 V l I 15 i l j i III F; i g :7 l6

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/l%%;\ A Tron/v45 y United States Patent SOAP MANUFACTURE Purdy Bradford, Palos Park, Ill., assignor to swift & Company, Chicago, 11]., a corporation of-Illmors Application May 21, 1951, Serial No. 227,328

4 Claims. (Cl. 260-417) The present invention relates in general to the production of low moisture content soap and, more particularly, to a method of low temperature saponification to produce directly a soap of a low moisture content.

The usual methods employed in the production of low moisture content soaps require either high temperatures or prolonged periods of time to complete the saponification. Additionally, the soap so produced must be subjected to a drying treatment to reduce the moisture content to the desired level.

In general, except for continuous processes, three methods are conventionally used in making soap, i. e., the boil, semi-boil, and cold-made processes. In the boiling process, the fats are saponified and the glycerin and some of the coloring matter removed by separating the aqueous solution from the soap by salting out or graining. After several of these washes or grainings, the soap is settled. The neat soap can be crutched and framed, or can be dried to form flakes or powder.

In the halfor semi-boiled process, all of the fat and caustic is added to a crutcher or similar mixer and saponified at a sulficiently high temperature to maintain the soap in a fiuid condition at all times. Because of the necessity of maintaining the mixture fluid, the moisture content of the soap must be maintained relatively high, requiring temperatures below the boiling point of water to be employed. It is possible to use higher temperatures if a high enough pressure is maintained on the mixer to prevent the vaporization of moisture. However, the use of such pressure requires expensive equipment and results in high maintenance costs.

In the so-called cold-made process, the fat and caustic are charged to a crutcher and partially saponified therein at relatively low temperatures until the resulting soap will satisfactorily emulsify the balance of the unsaponified fat and caustic so that no separation will occur when the mixture is dropped into a soap frame or other receptacle. The amount of water required in this mixture is relatively high in order to reduce the concentration of the remaining caustic soda to a point where it will not precipitate the soap from the emulsion. This process is generally used only on cocoanut oil soaps because these soaps can tolerate a higher concentration of caustic before being precipitated or grained. The moisture in the usual soap produced by this process is in the order of 30 per cent based upon the total Weight of the mixture.

It is an object of the present invention to provide an improved method for the manufacture of low moisture content soap.

It is an additional object to provide a method for the direct low temperature saponification of fats to produce a low moisture content soap.

Another object of the invention is to provide a method for saponifying fat with caustic wherein the mixture is maintained in a plastic state in contradistinction to the usual fluid or semi-fluid state required by prior art processes.

A further object of the invention is to provide a method ice of manufacturing a low moisture content soap by direct low temperature saponification wherein no subsequent drya ing operation is required.

Additional objects, if not specifically set forth herein, will be readily apparent to one skilled in the art from the following detailed description of the invention:

The drawing represents, for purposes of illustration, a diagrammatical view of one type of apparatus in which the present invention can be carried out.

Broadly, the present invention comprises subjecting a mixture of soap-forming ingredients in a plastic or semidry state to an intensive smearing and shearing action at relatively low temperatures and under atmospheric pres,- sure, whereby the mixture is completely saponified in a very short period of time.

More specifically, it has now been found that a mixture of soap-forming ingredients containing as small a percentage of moisture as may be desired is capable of complete saponification in a very rapid manner by causing the components of the mixture to be pressed into very intimate contact with one another through treatment in a particular type of reaction vessel. The intimate contact required is obtained only when the particles of the mixture are subjected to an intensive shearing and smearing action. The conventional crutcher or mixer used in soap mann facture will not produce this result. While the invention is not to be considered as limited to any one specific type of mixer or the like, it has been found that best results are obtained by use of a muller-type mixer.

Referring now to the drawing: The casing or body 10 of the muller is provided with a clean-out door 11. The door 11 is operated by pedals 12 and 13, one of which is for opening and one for closing the door. Heavy wheels or mullers 14 mounted within the body 10 are driven through a suitable means 15 located centrally of the body 10 so as to rotate both about their own axis and about the centrally-located drive means 15. These wheels, in

rotating about the floor of the body 10, provide tremendous shearing and smearing action on the material to be mixed which is caught between the wheels and the floor and crushed. The weight of the Wheels or mullers in the usual commercial type of apparatus will vary from 300 to 5500 pounds. The thickness of the muller will vary from 5 to 13 inches. Plows 16 are provided to rotate with the mullers and to scrape and continually re-feed the material into the paths of the mullers. This type of mixer is known to the art and since no restriction is desired to be placed on the invention by the equipment used, the foregoing description is considered sufiicient to adequately describe this type of apparatus to a worker skilled in the art.

Other types of apparatus may also be used, as for example, a screw-type extruder, a series of closely spaced rolls, or the like. The only limitation placed thereon is that whatever type of reactor is used, the mechanical pressure applied must be of a high order, and a shearing, smearing type of mixing must result.

The temperatures employed in the present invention are extremely low in comparison with the ordinary conventional saponification temperatures. Temperatures of F. or below may be used, but in general it has been found that the saponification rate is increased if heat is applied during the operation. As saponification increases, the heat liberated during the reaction naturally increases the temperature of themass. In general, mix temperatures in the range of F. P. are employed, but in no case is the temperature raised above the boiling point of water. As a convenient means of comparison with prior art processes, it may be said that the present invention employs the temperatures of the conventional cold-made process in producing directly in a much shorter time soaps containing any desired moiswater were added.

' with electrical strip heaters attached to the bed plate.

i mentioned above.

were added. This mixture was complete.

' Time in minutes:

. appeared complete; Then 764 parts far below that which can be obtained in the conventional cold-made process.

The following examples are set forth forthe purposebe construed as placing of illustration only andare not to any limitation on the scope of thepresent invention- Example 1 Using a muller type mixer, 5000 parts of prime tallow having a saponification number of 197 wereintimately mixed with 715 parts solid caustic soda containing 98 Saponification was started with the and after 15 minutes 715 parts of No heat was applied to the reaction other than that liberated in the reaction itself. Complete saponification resulted after 2 hours and 30 minutes per cent NaOH. dry caustic alkali,

of treatment in the muller, and the resulting soap was immediately milled to produce flakes.

' 1 Example 11 as in Example I and the remaining portion was mixed in the muller with small amounts of perfume, antioxidant and suflicient water to make the soap suitable for plodding, and then this mixed product was plodded and stamped into bars.

I I Example 111 Bleached, refined tallow (5000 parts) containing'0.38

per cent free fatty acid was first melted at 212 F. and then added to a cold mixer of the muller type. Caustic -(720 parts) and water (750 parts) were added and the mixture subjected to the action of the mullers for 2% hours, after which time 100 parts sodium pyrophosphate then allowed to stand overnight, atwhich time saponification was 100 per cent complete.

Example -IV The sameingredients as in Example 111 were subjected to the action of the mullers for a period of 3 hours, after which time saponification was approximately 90 per cent .Another batch of these same ingredients was mixed for 2% hours and it was found that saponification was 88.5 percent complete. A similar batch was then heated in the muller (as in Example II), and the temperature of the mass checked at various time intervals with the following results: 7

' Temperature, F. (internal soap) ture content, including soaps whose moisture content is V which may be used in the present r 45 r 165 '70' a.

' saponification completed temperature could not be measured because soap was hard. w

This latter batch of soap, after saponification was complete, was milled into very excellent flakes. Upon analysis it showed 1.28 per cent unsaponifiable material and 0.39 per cent unsaponifled material.

ExampleV Using a heated mixer as in Example 11,3880 parts of a bleached tallow, 562 parts flake caustic and 500 parts water were'mixed v for 55 minutes at which time the temperature was somewhat above 1709 F. and the reaction of 40 B. silicate of soda and 2.5 parts antioxidant were added and the soap mixed for S'minutes after which it was milled directly into flakes.

7 Example Vl In the same manner as in Example V, a mixture of 3940 parts bleached tallow, 438 parts bleached cocoanut oil, 652 parts flake caustic and 600 parts water was subjected to shearing and smearing pressure in'a muller-type mixer for 50 minutes. saponification was complete at this time, and after the addition and admixture with the soap of 5 parts antioxidant and 5 parts perfume, the soap was milled into flakes.

Example VII A fat mixture (4242. parts), consisting of 49.5 per cent light grease, 49.5 per cent #1 tallow, and l per cent rosin, was mixed with 604 parts flake caustic and 550 parts water. Thirty minutes subjection to the intensive shearing action of a muller type mixer resulted in a completely saponified soap which was then mixed with parts silicate and 5 parts antioxidant and milled into flakes.

It will be noted that in the foregoing examples the amount of moisture present in the saponifiable mixtures was very small in each case. The following table illustrates this fact and contrasts drastically the soap formulae invention with those required in prior art saponification processes wherein at least 30 per cent moisture/must be present in order to maintain the mixture in a fluid condition: I

Example No.2 Percent water in saponificable mixture 1 11.1

7 III' 11.6

- IV 11.6 V 10.1

VI 10.7 VII 7.45

As may be readily seen from the examples, complete saponification of the fats may be obtained with the stoichiometric amount of'caustic alkali and in the presence of little or no moisture. The soaps produced by this method do not'require drying since the moisture content maybe maintained at as low a level as desired in the saponification. The per cent moisture added to the saponification mixture and the per cent moisture in the saponified product may generaly be stated to be the same. The only exception would be instances in which the fat used contained appreciable percentages of free fatty acids. Moisture formed in the saponification of the fatty acids would be added to the moisture present in the original saponification mixture. In the usual case, the moisture so formed I from the fatty acids of the fat used is relatively insignificant and in any event can be compensated for by reduction in, the per cent moisture added. The soaps may, therefore, be directly milled into flakes or plodded into bars. Since ,there is no washing of the soap, the products of this invention contain all of the glycerin originally combined with the fatty acids of thefat. Thus, soap flakes having a very soft feel can be produced from tallow which would ordinarily produce only hard and brittle soaps.

The invention is believed .to be applicable to the saponification of any glyceride fat since tallow (used in the above examples) is one of the most. diflicult of all naturally occurring fats to saponify. In addition to tallow and mixtures thereof with other saponifiable materials, it is contemplated that all other well-known animal and vegetable oils, such as cottonseed oil, soybean oil, and the like, may

be treated in like manner by the method of this invention to produce soaps having any desired low moisture content.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without I claim:

1. In a method for the manufacture of low moisture content soap, the step comprising subjecting a saponifiable mixture in a plastic state to an intensive smearing and shearing pressure at temperatures below the boiling point of water whereby said mixture is saponified.

2. A method for the manufacture of low moisture content soap, comprising forming a mixture of saponifiable ingredients including caustic and water, regulating the amount of Water added so that the nature of said mixture is plastic, and subjecting said plastic mixture to an intensive mechanical shearing action while under high mechanical pressure and at a temperature below the boiling point of water whereby saponification of the mixture takes place.

3. A method for the manufacture of low moisture content soap, comprising adding to a mixture of saponifiable matter, containing only a small percentage of free fatty acids and solid alkali the amount of water desired in the final product, saponifying said mixture at a temperature content soap, the step comprising subjecting a saponifiable mixture, the water content of which ranges from zero per cent to not more than about 12 per cent by weight of the mixture at a temperature below the boiling point of Water, to an intensive shearing action and high mechanical pressure to substantially completely saponify said mixture.

References Cited in the file of this patent UNITED STATES PATENTS 1,560,626 Welter Nov. 10, 1925 1,722,687 Spensley July 30, 1929 2,325,320 Holuba July 27, 1943 

3. A METHOD FOR THE MANUFACTURE OF LOW MOISTURE CONTENT SOAP, COMPRISING ADDING TO A MIXTURE OF SAPONIFABLE MATTER. CONTAINING ONLY A SMALL PERCENTAGE OF FREE FATTY ACIDS AND SOLID ALKALI THE AMOUNT OF WATER DESIRED IN THE FINAL PRODUCT, SAPONIFYING SAID MIXTURE AT A TEMPERATURE BELOW THE BOILING POINT OF WATER BY THE APPLICATION THERETO OF AN INTENSIVE MECHANICAL SHEARING ACTION WHILE APPLYING HIGH MECHANICAL PRESSURES TO THE MIXTURE, AND RECOVERING 